JP4560837B2 - Pulley unit - Google Patents

Description

The present invention relates to a pulley unit, and more particularly to a pulley unit having low torsional rigidity.

Conventionally, a pulley unit is used by being mounted on, for example, a crankshaft of an automobile engine or an auxiliary machine attached thereto. In recent years, a pulley unit having a low torsional rigidity with improved rotational fluctuation absorbing performance has been proposed as a fuel efficiency measure.

As shown in FIG. 4, a conventional pulley unit having a low torsional rigidity includes a pulley 101, a hollow shaft 102, a torsion coil spring 131, a ball bearing 104, a bush 105, and a retaining ring 106. The part is composed.

The pulley 101 is rotationally driven by a crankshaft of an automobile engine, for example, via a V-rib shaped belt (not shown), and a wave-like groove around which the belt is wound is formed on the outer periphery thereof.

The hollow shaft 102 has a through hole in the center, and an input shaft (for example, a rotor of an alternator) attached to an automobile engine (not shown) is inserted into and fixed to the through hole. The hollow shaft 102 is inserted concentrically on the inner periphery of the pulley 101.

The torsion coil spring 131 is formed of, for example, a high-strength spring steel member and is formed into a coil having an organic square cross section. The torsion coil spring 131 is inserted in the middle of the outer periphery of the hollow shaft 102 and its axial base end (right end in FIG. 101 is fixed to the inner peripheral step surface, and the axial end (left end in FIG. 4) is fixed to the outer peripheral step surface of the hollow shaft 102.

The ball bearing 104 is disposed on the proximal end side of the hollow shaft 102 in the opposed annular gap between the pulley 101 and the hollow shaft 102, and includes a plurality of balls 141, an inner ring 142, an outer ring 143, and a plurality of balls. The holding ring 144 that holds 141 and the sealing ring 145 that shields the enclosed lubricating oil.

The bush 105 is disposed on the free end side of the hollow shaft 102 in the opposed annular gap between the pulley 101 and the hollow shaft 102.

The retaining ring 106 is fixed to the outer periphery of the proximal end of the hollow shaft 102 to prevent the ball bearing 104 from coming off the hollow shaft 102.

A seal ring 107 is attached to the free end in the axial direction of the pulley 101, and a predetermined lubricant is sealed in an opposed annular gap in which the ball bearing 104, the torsion coil spring 131, and the bush 105 are disposed. .

In such a conventional pulley unit, when the rotational speed of the pulley 101 becomes relatively higher than that of the hollow shaft 102, the torsion coil spring 131 is twisted so as to follow the rotation of the pulley 101 while absorbing the relative speed difference. The shaft 102 is rotated. Further, when the rotational speed of the pulley 101 becomes relatively slower than that of the hollow shaft 102, the torsion coil spring 31 is twisted in the opposite direction, and the hollow shaft 102 is rotated so as to pass the rotation of the pulley 101 while absorbing the relative speed difference. Allow.

In the conventional low torsional rigidity pulley unit, the resonance point is set to a frequency lower than the idle frequency. However, when the engine is started or stopped, the belt slips or squeals to pass the idle frequency occurs. There is.

For this reason, a pulley unit has been proposed in which a one-way clutch is provided so that the one-way clutch is disengaged even at a resonance frequency so that the resonance is not amplified (see, for example, Patent Document 1).
JP 2001-523325 A (pages 27-36, Fig. 2-5)

The conventional low torsional rigidity pulley unit described above has a structure that does not amplify resonance by disengaging the clutch even at the resonance frequency by providing a one-way clutch. However, the one-way clutch is added to increase the size and cost. There is a problem of being up.

In view of such circumstances, the present invention provides a belt slip mechanism without increasing the physique and cost by providing a spring clutch mechanism using a torsion coil spring that is already disposed in a pulley unit with low torsional rigidity. It aims to solve the problem of squealing and belts.

Means for Solving the Problems and Effects of the Invention

Pulley unit of the present invention includes a shaft body and ring member disposed concentrically, is inserted into the shaft body while being fixed to the ring body, opposite the annular gap between the ring member and the shaft member a torsion coil spring interposed, in a low torsional rigidity of the pulley unit comprising a rolling bearing and disposed on at least one side, of the torsion coil spring in the opposite annular gap was fixed at one end to said ring member and the torsion coil spring, a ratchet having an engagement surface the end of which one end is disposed on the shaft body other engages the free end of the torsion coil spring, the engaging surface of the ratchet A biasing means for biasing the torsion coil spring in a direction to engage with the free end, and transmitting one rotation of the ring body to the shaft body via the torsion coil spring and the ratchet; Annulus Pulley unit square rotation of which is characterized in that it comprises a spring clutch mechanism which is not transmitted to the shaft body. According to such a pulley unit, it is possible to prevent belt slipping and squealing at a resonance point with a small physique and low cost as compared with a type in which a one-way clutch is separately added.

Further, the ratchet may be the free end of the torsion coil spring is arranged freely floating and sinking in the housing recess formed in the sliding surface of the shaft for sliding. Therefore, since no new parts are required for the ratchet arrangement, the ratchet can be arranged very easily and inexpensively.

Furthermore, the ratchet is, the surface end portions opposite to the engaging surface is in contact arrangement with the housing recess bored in the sliding surface of the shaft body is an arcuate surface, facing the torsion coil spring the can be a higher becomes higher inclined slope towards the engagement surface direction from the arcuate surface. Therefore , the ratchet swings around the arc surface, and engagement and disengagement with the ratchet accompanying rotation of the torsion coil spring can be controlled smoothly.

Then, the biasing means may be formed by stretching of the coil spring is arranged interposed between said said housing recess drilled in the shaft ratchet. For this reason , it is possible to smoothly control the rising and sinking of the ratchet with respect to the housing concave portion accompanying the rotation of the torsion coil spring without the urging means coming into contact with the torsion coil spring.

Also, ratchet have a biasing resilient, the ratchet can also serve as also the biasing means. Therefore, since the ratchet has elasticity to urge itself in a direction to engage with the torsion coil spring, the spring clutch mechanism can be configured with a small number of parts.

The ratchet is composed of a spring washer, and one end surface of the spring washer is the engagement surface that engages with the free end of the torsion coil spring , and the other end surface is a sliding contact surface of the shaft body. It can be accommodated in the perforated storage recess, and the spring seat surface of the spring washer can be an inclined surface that becomes higher in the engagement surface side direction . Therefore, since the spring washer is used as a ratchet, the spring clutch mechanism can be configured very simply by the spring washer and the torsion coil spring.

In the pulley unit with low torsional rigidity, the problem of belt slipping and squealing at the resonance point is eliminated without increasing the physique and cost by providing a spring clutch mechanism that uses a torsion coil spring that is already installed. did.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of the pulley unit according to the first embodiment of the present invention along the axial direction. The pulley unit according to the first embodiment includes a pulley 1, a hollow shaft 2, a spring clutch mechanism 3, a ball bearing 4, a bush 5, and a retaining ring 6, and main parts thereof are configured.

The pulley 1 is driven to rotate by a crankshaft of an automobile engine, for example, via a V-rib shaped belt (not shown), and a wave-like groove around which the belt is wound is formed on the outer periphery thereof.

The hollow shaft 2 has a through hole in the center, and an input shaft (for example, a rotor of an alternator) attached to an automobile engine (not shown) is inserted into and fixed to the through hole. The hollow shaft 2 is inserted concentrically on the inner periphery of the pulley 1. In order to allow the bush 5, the spring clutch mechanism 3 and the ball bearing 4 to be easily assembled in this order from the axial base end side into the opposed annular gap between the pulley 1 and the hollow shaft 2, the hollow shaft 2 The outer diameter dimension corresponding to 5, the outer diameter dimension corresponding to the spring clutch mechanism 3, and the outer diameter dimension corresponding to the ball bearing 4 are decreased in this order.

The spring clutch mechanism 3 is interposed in the center in the axial direction of the opposed annular gap between the pulley 1 and the hollow shaft 2, and a torsion coil spring 31 inserted into the hollow shaft 2 and a torsion coil spring 31. The ratchet 32 is engaged with the free end 31a, and the biasing spring 33 is a coil spring that biases the ratchet 32.

The torsion coil spring 31 is formed of a high-strength spring steel member, for example, as a coil having an organic quadrangular cross section, and its base end is fixed to the inner circumferential step surface of the pulley 1 by, for example, press fitting, and the free end 31a. Is freely engageable with and disengageable from the engaging surface 32a of the ratchet 32 (see FIG. 2A)).

As shown in FIGS. 2A and 2B, the ratchet 32 has a slidable contact surface 32 c formed on the upper surface of the ratchet 32 in the synchronous rotation direction between the torsion coil spring 31 and the hollow shaft 2. The inclined surface becomes higher as it goes, and the side surface opposite to the direction of synchronous rotation between the torsion coil spring 31 and the hollow shaft 2 (that is, the side surface opposite to the engaging surface 32a) is an arc surface 32d. The ratchet 32 swings about the circular arc surface 32d, so that the ratchet 32 can smoothly float and sink with respect to the storage recess 21 as the torsion coil spring 31 rotates.

The urging spring 33 is formed of, for example, an extensible coil spring (see FIGS. 2A and 2B), and is a hole formed in the housing recess 21 of the hollow shaft 2 and the bottom wall of the ratchet 32. It is inserted and arranged between 32b. Due to the expansion elasticity of the biasing spring 33, the ratchet 32 is normally levitated from the inside of the housing recess 21 and engages the engaging surface 32a with the free end 31a of the torsion coil spring 31 (FIG. 2 (a )reference)). However, when a rotational force in the direction opposite to the synchronous rotational direction is applied to the torsion coil spring 31, the ratchet 32 is pushed by the torsion coil spring 31 and sinks into the storage recess 21 as shown in FIG. The torsion coil spring 31 is released without being locked. In the first embodiment, the urging spring 33 formed of an extensible coil spring is used as the urging means. However, other urging means such as a leaf spring may be used.

The ball bearing 4 is disposed on the proximal end side of the hollow shaft 2 in the opposed annular gap between the pulley 1 and the hollow shaft 2, and includes a plurality of balls 41, an inner ring 42, an outer ring 43, and a plurality of balls A holding ring 44 that holds 41 and a sealing 45 that shields the enclosed lubricating oil. The inner ring 42 is fixed to the outer peripheral surface of the hollow shaft 2 by, for example, press fitting. The outer ring 43 is fixed to the inner peripheral surface of the pulley 1 by, for example, press fitting. In the first embodiment, the ball bearing 4 is used as a rolling bearing, but a roller bearing can be used instead of the ball bearing 4.

The bush 5 is disposed on the free end side of the hollow shaft 2 in an opposed annular gap between the pulley 1 and the hollow shaft 2. The bush 5 is formed in a ring shape with a lubricant-impregnated metal or the like, and is fitted and fixed to the inner peripheral surface of the pulley 1. The inner peripheral surface of the bush 5 is in frictional sliding contact with the outer peripheral surface of the hollow shaft 2. In the first embodiment, the bush 5 is used, but a rolling bearing made of a ball bearing or a roller bearing can also be used.

The retaining ring 6 is fitted and fixed to the outer peripheral surface of the proximal end of the hollow shaft 2 by, for example, press fitting to prevent the ball bearing 4 from coming off the hollow shaft 2.

A seal ring 7 is attached to the free end of the pulley 1 in the axial direction, and a predetermined lubricant is enclosed in an opposed annular gap in which the ball bearing 4, the spring clutch mechanism 3 and the bush 5 are disposed. .

2A and 2B are schematic diagrams for explaining the operation of the torsion coil spring 31 and the ratchet 32. FIG. 2A and 2B are diagrams for explaining the operation to the last, and the dimensional relationship of each member in FIG. 1 is not maintained.

Next, the operation of the pulley unit according to the first embodiment configured as described above will be described with reference to FIGS. 1 and 2.

When the driving force of the belt is applied to the pulley 1 by starting the engine or the like, the pulley 1 rotates (hereinafter, this rotational direction is referred to as a synchronous rotational direction), and as shown in FIG. The torsion coil spring 31 with the base end fixed also starts to rotate in the synchronous rotation direction indicated by the arrow. Then, the torsion coil spring 31 engages the free end 31 a with the engagement surface 32 a of the ratchet 32 floating from the storage recess 21 of the hollow shaft 2. For this reason, the hollow shaft 2 to which torque is applied from the torsion coil spring 31 also starts to rotate in the synchronous rotation direction together with the pulley 1 and the torsion coil spring 31. As the driving force applied to the pulley 1 from the belt increases, the torsion coil spring 31 continues to transmit torque to the hollow shaft 2 via the ratchet 32 while increasing the deflection within the stress range. Continue to rotate. When the rotation of the pulley 1 reaches a constant speed, the pulley 1 and the hollow shaft 2 are integrated and continue to rotate synchronously.

On the other hand, if the driving force of the belt decreases due to the deceleration or stop of the engine, etc., the rotational speed of the pulley 1 decreases accordingly, but the hollow shaft 2 is a mechanically coupled device (for example, an alternator). It tries to keep rotating at a high rotational speed against the speed change due to inertia. Then, since the rotational speed of the pulley 1 becomes relatively slower than the rotational speed of the hollow shaft 2, the torsion coil spring 31 is synchronously rotated relative to the hollow shaft 2 as shown in FIG. And the free end 31a is separated from the engagement surface 32a of the ratchet 32 and becomes free. At the same time, the sliding contact surface 32 c of the ratchet 32 is pushed by the rotation of the torsion coil spring 31 in the direction opposite to the relative synchronous rotation direction, and the ratchet 32 is stored against the expansion elasticity of the biasing spring 33. It sinks into the recess 21. For this reason, the torque transmitted from the pulley 1 to the hollow shaft 2 via the torsion coil spring 31 is interrupted, and the hollow shaft 2 continues to rotate only by the rotational inertia force. That is, when the coil spring 31 is disengaged from the ratchet 32, the rotational inertia force of the hollow shaft 2 is temporarily released.

Thus, according to the first embodiment, the spring clutch mechanism temporarily releases the rotational inertia force of the hollow shaft 2 under the deceleration condition of the pulley 1, so that the pulley 1 due to excessive twisting of the coil spring 31. Further, the vibration of the hollow shaft 2 is suppressed, and belt slippage and squealing at the resonance point can be effectively prevented.

Moreover, since the application of excessive rotational inertia force to the pulley 1, the torsion coil spring 31 and the hollow shaft 2 is suppressed, the durability of the pulley unit is improved.

Furthermore, compared with the case where a conventional one-way clutch is added, the number of parts is extremely small, and only the ratchet 32 and the urging spring 33 are substantially increased. It becomes possible to prevent belt slippage and belt squeal at points.

Incidentally, when the pulley unit of the first embodiment is applied to the alternator of the vehicle engine, the rotation of the alternator rotor is maintained in a high rotation range regardless of the rotational fluctuation of the crankshaft of the engine that is the driving source of the belt. Efficiency can be increased. That is, when the rotation speed of the crankshaft increases, the spring clutch mechanism 3 is locked and rotates the hollow shaft 2 synchronously with the pulley 1. On the other hand, when the rotation speed of the crankshaft decreases, the spring clutch mechanism 3 is free. In this state, the hollow shaft 2 can be continuously rotated by its own rotational inertia force regardless of the deceleration of the pulley 1. Thereby, it can also contribute to the improvement of the fuel consumption efficiency of a vehicle.

FIG. 3 is a perspective view of a main part of the pulley unit according to the second embodiment of the present invention. In the pulley unit according to the second embodiment, the ratchet 32 is formed of a C-shaped spring washer as shown in FIGS. 3 (a) and 3 (b), and is formed on the inner peripheral step surface of the hollow shaft 2. It is stored so as to be fitted into a storage recess 21 formed by a C-shaped groove. The spring washer is formed by twisting an elastic metal plate such as stainless steel, phosphor bronze or the like so as to draw a spiral about the plate thickness in one round, and a spring seat surface 32e formed on one end side surface thereof is a torsion coil spring. The engagement surface engages with the free end 31a of 31.

Since other members not particularly mentioned are formed in the same manner as the pulley unit according to the first embodiment shown in FIG. 1 and are arranged in the same manner, their detailed description is omitted. Further, FIG. 3 is a diagram for explaining the main part to the last, and the dimensional relationship of each member in FIG. 1 is not maintained.

Next, the operation of the pulley unit according to the second embodiment configured as described above will be described with reference to FIGS. 1 and 3.

When the driving force of the belt is applied to the pulley 1 by starting the engine or the like, the pulley 1 rotates in the synchronous rotation direction, and the torsion coil spring 31 whose base end is fixed to the pulley 1 also starts to rotate in the synchronous rotation direction. . And the torsion coil spring 31 engages the free end 31a with the spring seat surface 32e of the ratchet 32 which consists of the spring washer which floats from the storage recessed part 21 of the hollow shaft 2, as shown to Fig.3 (a). Let For this reason, the hollow shaft 2 to which torque is applied from the torsion coil spring 31 also starts to rotate in the synchronous rotation direction together with the pulley 1 and the torsion coil spring 31. As the driving force applied to the pulley 1 from the belt increases, the torsion coil spring 31 continues to transmit torque to the hollow shaft 2 via the ratchet 32 while increasing the deflection within the stress range. Continues to rotate in the synchronous rotation direction. When the rotation of the pulley 1 reaches a constant speed, the pulley 1 and the hollow shaft 2 are integrated and continue to rotate synchronously.

On the other hand, when the driving force of the belt decreases due to deceleration or stop of the engine, the rotational speed of the pulley 1 decreases. However, the hollow shaft 2 changes in speed due to the inertia of a mechanically coupled device (for example, an alternator). It tries to keep rotating at a high rotation speed against this. Then, since the rotational speed of the pulley 1 becomes relatively slower than the rotational speed of the hollow shaft 2, the torsion coil spring 31 rotates relative to the hollow shaft 2 in the direction opposite to the synchronous rotational direction. The free end 31a is separated from the spring seat surface 32e of the ratchet 32 made of a spring washer, and becomes free. At the same time, the sliding contact surface 32c, which is the upper surface of the ratchet 32, is pushed by the rotation of the torsion coil spring 31 in the direction opposite to the relative synchronous rotation direction, and as shown in FIG. The ratchet 32 is sinked into the housing recess 21 against its own elasticity. For this reason, the torque transmitted from the pulley 1 to the hollow shaft 2 via the torsion coil spring 31 is interrupted, and the hollow shaft 2 continues to rotate only by the rotational inertia force. That is, when the coil spring 31 is disengaged from the ratchet 32, the rotational inertia force of the hollow shaft 2 is temporarily released.

For this reason, it cannot be overemphasized that the same effect as the pulley unit concerning Example 1 is acquired also in the pulley unit concerning Example 2. In addition, since the ratchet 32 is formed of a spring washer, the ratchet 32 can be urged within the storage recess 21 without providing an urging means separately. For this reason, the pulley unit can prevent belt slipping and squealing at the resonance point without substantially increasing the physique and cost only by increasing the ratchet 32.

Further, since the number of parts is small, the durability of the pulley unit can be improved accordingly.

The embodiments of the present invention have been described above. However, these are merely examples, and the present invention is not limited thereto, and the knowledge of those skilled in the art can be used without departing from the scope of the claims. Various modifications based on this are possible. For example, the present invention includes a structure in which the pulley 1 and the hollow shaft 2 are also used as the inner and outer rings of the spring clutch mechanism 3, the ball bearing 4 and the bush 5, respectively.

Sectional drawing which follows the axial direction of the pulley unit which concerns on Example 1 of this invention. The schematic diagram explaining operation | movement with the torsion coil spring and ratchet in FIG. The schematic diagram explaining operation | movement with the torsion coil spring and ratchet in the pulley unit which concerns on Example 2 of this invention. Sectional drawing which follows the axial direction of the conventional pulley unit.

Explanation of symbols

1 Pulley
2 Hollow shaft (shaft)
3 Spring clutch mechanism 4 Ball bearing (rolling bearing)
5 Bush 6 Retaining Ring 21 Storage Recess 31 Torsion Coil Spring 32 Ratchet 32a Engagement Surface 32b Hole 32c Sliding Contact Surface 32d Arc Surface 32e Spring Seat Surface 33 Biasing Spring (Biasing Means)

Claims (6)

A shaft and a ring arranged concentrically;
Wherein is inserted into the shaft body while being fixed to the ring member, and a torsion coil spring interposed opposing annular gap between the ring body and the shaft body,
A rolling bearing which is disposed on at least one side of the torsion coil spring in the opposite annular gap,
In a low torsional rigidity pulley unit comprising:
The torsion coil spring having one end fixed to the ring body ;
A ratchet having one end portion disposed on the shaft body and the other end portion having an engagement surface that engages with a free end of the torsion coil spring;
A biasing means for biasing the engagement surface of the ratchet in a direction to engage with the free end of the torsion coil spring ;
By
A pulley comprising a spring clutch mechanism that transmits one rotation of the ring body to the shaft body via the torsion coil spring and the ratchet, and does not transmit the other rotation of the ring body to the shaft body. unit. The ratchet have a biasing resilient, pulley unit according to claim 1 wherein the ratchet is characterized that you have also serves as the biasing means. 2. The pulley unit according to claim 1, wherein the ratchet is disposed so as to be able to float and sink in a storage recess formed in a sliding contact surface of a shaft body in which the free end side of the torsion coil spring contacts. . The ratchet is
The end opposite to the engagement surface is an arc surface and is disposed in the storage recess formed in the sliding contact surface of the shaft body,
Pulley unit according to claim 3, characterized in that that the torsion coil spring which faces, Tsu Do and more becomes higher inclined slope towards the engagement surface direction from the arcuate surface. Said biasing means, the claims have been formed in the stretchable coil spring, characterized in that interposed in is disposed between the shaft drilled the housing recess in the ratchet 4. The pulley unit according to 4 . The ratchet is composed of a spring washer, and one end surface of the spring washer serves as the engagement surface that engages with the free end of the torsion coil spring , and the other end surface is formed in the sliding contact surface of the shaft body. have been accommodated in has been the accommodating recess, a pulley unit according to claim 3, a spring seat surface of the spring washer, characterized in that an inclined surface becomes higher toward the engagement surface direction.

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